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Mirror Neurons and Colamus Humanitatem

Mirror Neurons and Colamus Humanitatem

Why our brains cherish humanity: Mirror neurons and colamus humanitatem

JOHN R. SKOYLES* Centre for Mathematics and Physics in the Life Sciences and Experimental Biology (CoMPLEX) University College London, London, UK Centre for Philosophy of Natural and Social Science (CNPSS) London School of Economics, London, UK

Abstract Resumen

Commonsense says we are isolated. After all, our El sentido común dice que estamos aislados. Des- bodies are physically separate. But Seneca’s cola- pués de todo, nuestros cuerpos están separados mus humanitatem, and John Donne’s observation físicamente. Pero la obra Colamus humanitatem that “no man is an island” suggests we are neither de Séneca y la observación de que “ningún hombre entirely isolated nor separate. A recent discovery in es una isla”, que hizo John Donne, sugieren que no —that of mirror neurons—argues that estamos ni completamente aislados ni separados. the brain and the is neither built nor functions Un descubrimiento reciente de la neurociencia, el remote from what happens in other individuals. de las neuronas espejo, sostiene que el cerebro y What are mirror neurons? They are brain cells la mente no son construidos ni funcionan alejados that process both what happens to or is done by an de lo que pasa en otros individuos. ¿Qué son las individual, and, as it were, its perceived “refl ec- neuronas espejo? Son células cerebrales que pro- tion,” when that same thing happens or is done by cesan tanto lo que le pasa como lo que hace un in- another individual. Thus, mirror neurons are both dividuo, y, por así decirlo, su “refl exión” percibida activated when an individual does a particular ac- cuando esa misma cosa le pasa a, o es hecha por, tion, and when that individual perceives that same otro individuo. Por lo tanto, las neuronas espejo action done by another. The discovery of mirror se activan cuando una persona realiza una acción neurons suggests we need to radically revise our específi ca y cuando percibe la misma acción rea- notions of nature since they offer a means lizada por otro. El descubrimiento de las neuronas by which we may not be so separated as we think. espejo indica que es preciso revisar radicalmente unlike other are adapted to mirror nuestras nociones sobre la naturaleza humana, ya interact nonverbally when together. Notably, our que estas neuronas ofrecen un medio por el cual no faces have been evolved to display agile and nim- concebimos estar tan separados como pensamos. ble movements. While this is usually explained A diferencia de otros simios, los humanos están as enabling nonverbal , a better adaptados a interactuar de forma similar no verbal, description would be nonverbal commune based cuando están juntos. De manera particular, nuestras upon mirror neurons. I argue we cherish humanity, caras han evolucionado para mostrar movimientos colamus humanitatem, because mirror neurons and ágiles y rápidos. Mientras esto usualmente expli- our adapted mirror interpersonal interface blur the ca cómo se logra la comunicación no verbal, una physical boundaries that separate us. mejor descripción sería la comunicación no verbal

* Please send correspondence to: John R. Skoyles. Centre for Mathematics and Physics in the Life Sciences and Experimental Biology (CoM- PLEX), University College London. 4 Stephenson Way, London NW1, 2HE, UK. E-mail: [email protected].

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Key words: mirror neurons, empathy, self, social basada en las neuronas espejo. El autor sostiene emotions, interpersonal communication, commu- que valoramos la humanidad, colamus humanita- nitas. tem, porque las neuronas espejo y nuestra interfaz interpersonal adaptada de espejo desdibujan las fronteras que nos separan. Palabras clave: neuronas espejo, empatía, sí mismo, emociones sociales, comunicación inter- personal, sentido de comunidad.

Why cherish humanity—Seneca’s colamus huma- isolated as if were an island. As the social psycholo- nitatem? Why care about other people? Why should gist James Fiske has observed: “From Freud to so- we go beyond the boundaries of our own personal ciobiologists, from Skinner to social cognitionists, lives and value the lives of other men and women? from Goffman to game theorists, the assumption in Is it, perhaps, because we are all members of the Western psychology has been that humans are by same species, sapiens sapiens? Or, maybe, nature asocial individualists ... social relationships it is because when I see another person in , I are instrumental means to nonsocial ends, or cons- know rationally that what they experience is much traints on the satisfaction of individual desires” the same as when I suffer myself pain? But these (1992, p. 689). And again, as another psychologist, answers are not by themselves convincing: for, C. Daniel Batson has observed, “Perhaps the rea- why should the fact that other people are like me son that psychologists have spent little time on the either in body or in their capacity for experiences question of our social nature is because they already such as pain, cause me to care or cherish them? know the answer... our behavior may be highly so- We do this—and feel we ought to—but it is not cial; our also may be highly social; but in a logical necessity. After all, the cells of my body our hearts, we live alone... We are social egoists” under the might be much like those of (1990, p. 336). earthworms or some other lowly creature but that Neuroscience, as I will show here, provides does not mean I should necessarily value the life of grounds for rejecting the idea that we are “asocial earthworms. Yet Seneca’s observation about 2000 individualists” and “social egoists.” By , years ago touches a deep insight as to human na- we now know that the neural fabric out of which ture and what it is to be a human. An unidentifi ed each of our is woven is such that the lives and aspect about being a human exists that causes us experiences of other people are as vital to us as our to cherish other people. As John Donne once noted own. The neuroscience discovery which is respon- in his Devotions that “no man is an island, entire sible for this goes by the name of “mirror neurons.” to itself,” and “Any man’s death diminishes me, These neurons, I shall argue, support John Donne because I am involved in Mankind.” Here poets and Seneca’s view of . Neurologica- catch a truth—but what kind of truth is it—for it is lly, no brain is an island. Our neurons wire us to not one of logic. Can science illuminate this aspect exist within, to use a Latin word for “common”, as of our unknown humanity? a nonverbal communio, or commune. Here, however, is not a problem that most psy- chologists and philosophers seek to fathom. Rather What are mirror neurons? scholarly and scientifi c attempts to understand the nature of humanity mostly start from the premise To understand mirror neurons, we need fi rst to that other people’s experience does not funda- appreciate how the brain was traditionally—and mentally matter. Yes, people may say words about mistakenly— to work. If one looks at a valuing others for courteous appearances but that diagram of the brain, it is labeled with terms such underneath each of our minds really in fact lives as as visual, auditory and motor. Thus, there is the

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at the back of the brain that indicates applies to actions done by bodies – those done by that this area handles sight, and the motor cortex robots do not activate these neurons (Tai, Scherfl er, in the front that this area deals with the body’s Brooks, Sawamoto, & Castiello, 2004). Such brain movements. These areas have divisions; hence areas respond, moreover, not only to the sight of the motor cortex gets divided up, for example, other movements but also their perception through into the primary motor cortex and the premotor sound (Galati et al., 2008). (This might seem an cortex. There are good reasons for the existence obscure point but in fact our vocal ability to pro- of these terms—injury to the visual cortex causes nounce a word or name that we have just overheard blindness and, likewise, injury to the motor cortex depends upon such auditory-motor mirroring.) The causes paralysis. This labeling has turned out howe- activation of mirror neurons occurs even when the ver to cause false expectations about the workings object of an action is hidden, provided the intention of the brain. One of them is that the function of the of the goal of the movement is clear (Umilta et al., motor cortex areas does not include also an impor- 2001). Mirroring applies to emotional expression tant role in perception. After all, labels for percep- and experience also, for example, when we see the tion such as vision and audition have been given to expression of disgust on the face of another person parts of the brain elsewhere. So it was unexpected after smelling a revolting odor, we activate the sa- when in 1992 that Giacomo Rizzolatti and collea- me areas in our own brain (the anterior insular—a gues of Parma University (1992) found that certain part of the emotional brain near the motor cortex) neurons in a part of the motor cortex, the F5 inferior that gets activated when we ourselves smell that premotor area, had a role in perception. The motor odor and express disgust (Wicker et al., 2003). If cortex here did not only control the body as might we see another individual with an on their be inferred from the label but also perceived the hand that gives painful shocks and then a cue when movement of other individuals. they are electrocuted, many of the same parts of our Rizzolatti’s initial work involved macaque brains get activated as when we receive an electric monkeys using implanted in their shock (Singer et al., 2004). brains. What he found was that certain neurons in Mirror neurons, or neurons related to them are their motor cortex discharged when they did a par- found outside the motor cortex. Mirror neurons ticular hand action, say reaching to grasp a raison, are found in the posterior parietal cortex, though while others were activated by other actions such these neurons are concerned with the kinesthetic as tearing something up. Nothing surprising here. and somatosensory aspects of actions rather than What was unexpected was that the same neurons their execution. As already noted, mirror neurons also discharged when they saw another monkey or related to affective reactions such as disgust are the experimenter doing these same actions. Thus, found in the insula cortex suggesting the existence a neuron would spike when a monkey grabbed a of mirror neurons for the expression of emotions. raison and also when it saw the experimenter grab Mirror neuron-like cells have also been found in the one, and different neurons would be activated for superior temporal sulcus area. These neurons are different actions such as tearing and seeing another particularly interesting because though they are not individual tearing. Neurologically, these neurons activated by a person’s own movement, they get acti- were like mirrors refl ecting what others did in the vated by what is called “biological motion” (Johans- external world onto the brain doing same actions. son, 1973). To gain a sense of what biological mo- Since 1992 several more things have been es- tion entails, imagine a person masked and wearing tablished about mirror neurons. They are not con- black in a black room with diodes attached to fi ned to monkeys: functional brain imaging and their limbs so they cannot be seen; only the dots of other techniques fi nds them also in humans. When light they are wearing. Remarkably, when an indi- people observe actions made by other individuals, vidual walks, jumps and in other ways moves—the much the same areas in their brains lighted up as movement of the light dots lets us identify instantly when they perform them. Such mirroring only what they are doing, even though we cannot see

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their actual bodies. People have been found to be actual bodily actions—we improve our skills in able to identify immediately not only what someo- them. One explanation is that what we are doing is ne is doing—walking, dancing, and so on—from rehearsing the motor goals which organize actual the movements of such light dots, but also their movements. Motor skill requires the ability to co- gender and who the individual is—we each have ordinate together such goals— to tie a knot our own movement signature. Interestingly, we can is less a skill in movement than doing actions in the identify such movements as having been made by right order. More is involved in the link between us rather than someone else which is remarkable and actual processing than this though since we never or only rarely see our own actions. since it applies also to when we visualize in our The existence of mirror neurons might on fi rst imagination seeing an object. When we do this we impressions seem rather odd. But there is a subtle activate many of the same visual areas involved logic at work if we appreciate that the general wor- when we actually recognize and see that object. A kings of the motor cortex is not like that implied general rule of function in the brain seems to be that by most diagrams of its functioning. This is often online and offl ine processing take place in many of of some piano-like mechanism in which motor the same brain areas. neuron activation as it were hit keys that then act Motor imagination concerns our own move- like hammers upon strings upon the body’s mus- ments but it readily blends into mirroring the actual cles. The motor cortex is not like this, for a start it world. For example, when asked to judge whether is not a motor-muscle cortex as much as a motor- a glove shape fi ts the left or right hand, we activa- goal one. While there is a homunculus general te a part of the appropriate right or left side of the layout of the body on the motor cortex, it is very motor area in our brains that controls which of our much more rough than, say the one for our sense hands would fi t that glove. We, in a sense, identify of touch upon our body in the somatosensory cor- whether a glove would fi t our left or right hand by tex, or the in the visual cortex. This refl ects imagining the appropriate part of our body and the fact that the motor cortex does not control seeing how it would fi t into the glove (Parsons muscles, but a much higher level of movement et al., 1995). It is a small jump from this for such creation—that concerned with programming motor neurons in their processing to imagine what it is goals. Such programming is unlike that done by any like to be another. robot—if we make a reaching movement to grab, say, an apple, and our hand receives a sudden jolt Motor perception that displaces it from its planned course, our motor system automatically compensates so that our hand The neuroscience discussed above gains its full still reaches its target—the apple. No robot can do importance from what psychologists have found this. The motor cortex is concerned with processing about movement and perception. In what follows, the motor goals, like reaching the apple, rather than I am slightly speculative because the phenomena processing the particular muscles used by our arm I mention have not all so far been linked directly and hand. to the mirror neurons and the motor cortex. But This higher level of processing allows the mo- that is due to lack of research, not lack of logical tor cortex to process movements independently connection. of the body, for example, when we imagine, as if, Ten years before Rizzolatti’s discovery of mi- making an action in “our heads.” When we menta- rror neurons, for example, Jennifer Freyd found that lly imagine in this way making a motor action, we people after seeing a photograph of a human action light up much the same parts of the brain that get had diffi culties rejecting other pictures from a se- activated when we actually make that movement. quence of photos of the action taken later on (1982). Here, we are as it were mirroring not another’s ac- This suggested that when people had looked at tion but our own in our own thoughts. The curious that static , they had storied it in terms of its thing is that such imagination has real effects on dynamic body movement—which would suggest

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that when we look at actions we do not recognize letters at least in part from the dynamic information them as objects but in terms of their actions. It is their drawing strokes contain about how they were reasonable to suggest that this happens in motor written. If you look closely at the strokes of letters, neurons responsible in us for controlling the sa- they have slightly different and curves de- me kind of movement. In another case of motor pending upon which letter preceded them. The ellip- perception Jennifer Freyd and Maggie Shiffrar tical beginning of the stroke starting the letter “l” (1990) found that when we see “apparent motion” after another “l” has a different shape to that after between two alternating static pictures of a per- an “m.” The brain when looking at the lines making son doing an action, what we see links not to the up such letters picks up from such clues how they shortest possible path between the two but were written to identify what they are. And this to the anatomical plausible action that links them. applies not just to alphabetic handwriting: Jean- Again, this suggests that our perception of bodily Pierre Orliaguet in (1997) has found that movements happens not in terms of objects but in Chinese logographs are perceived in terms of the terms of knowledge held in the motor cortex as to fl ow of the movement strokes used to paint them. how our own movements could carry them out. In This would seem a factor in the perception of Chi- a sense, the brain sees the actions of others by pa- nese and Japanese logographs which are often learnt rasitizing its own knowledge of the actions it can fi rst by learning how to draw them. A group from do with its body. Japan has even reported motor cortex activation But perception must go much deeper than even accompanies the perception of oriental . this. Take the following example of motor per- ception found in the created fi rst by Paolo Mirror neurons and human nature Viviani at the University of Geneva (1992). Here Paolo Viviani presented a light dot on a screen mo- Why do mirror neurons exist? One idea is that they ving repetitively around an elliptical path. What might have arisen to aid motor imitation. Individual is odd is that when people look at its movement, monkeys spend months learning skills such as how they see it as only uniform if it imitates the biome- to best crack open a nut – it would advantage ano- chanical constraints of a human hand moving the ther monkey to get a head start on learning that skill dot along that path—faster when curvature is less, by observation. However, learning by imitation is slowing down at the sharper ends. Such percep- unlikely why mirror neurons arose. First, as noted, tion is so powerfully shaped by our sense of action they exist due to how the motor cortex organizes that Viviani found that a gradual shift of the path actions in terms of goals. This suggests that when to a circle went unnoticed providing the elliptical a mirror neuron is activated by an observed action, velocity was retained. Here, our perception is of it is a case of what Stephen Gould called an exapta- an abstract movement that we could make. Again, tion (Gould & Vrba, 1982). An exaptation contrasts this suggests that mirror neurons enable us to see to an adaptation -- in an adaptation, the origin of the world fi lled not so much in terms of objects as a thing arises from its utility, but with an exapta- with actions which with we, as if as it were, “em- tion, its origins come from it being a fortuitous and pathize.” incidental side effect of something else—in the case Such motor empathy can be practical in various of mirror neurons, to the already existing processes ways. Consider the problem of recognizing cursi- of motor neurons. A second reason is that nonhu- vely joined handwritten letters. We do it automa- man do not readily imitate. This may be tically, but there are few clues as to which letter surprising—after all, “to ” means “to copy.” But strokes matches which alphabetic letter—it is not in spite of intense research, the search for evidence like identifying an object where we are presented that monkeys and imitate, has not been with many sources of information in the form of co- very fruitful—the conclusion is that in general “apes lor, form and shape. Mary Babcock of Cornell Uni- do not ape.” This applies not just to the copying of versity (1988) has found that people identify cursive body movements but also vocalizations.

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Evolution could, however, have developed walking. But your fi ngers and thumb are just the mirror neurons, once they had arisen as part of right lengths to work easily with each other—just the motor cortex. Exaptations—incidental side play around with your hands and you will feel how effects—can be the raw stuff upon which natural your fi ngers and your thumbs fi t. To carrying selection works. Further, and this is an idea that I body weight, wrists and fi ngers liga- will now expand upon—mirror neurons could have ments are thick and strong, but those in our hands shaped the of the body. The nature of this are only stiffened suffi ciently to enable dexterous will become clearer in the next sections. In these I fi nger movements. shall argue that changed us so it There is another factor: feel the tips of your could exploit mirror neurons. This story, I suggest, thumb and fi ngers; they have broad nails and soft underlies our ability to create , language, so- fl esh pads. Prick them and they bleed as they are ciability, cognitively put ourselves in other people’s rich in blood vessels—these are need to support a “,” and even the very reason why we seek to skin dense with sensory nerve endings. Such sen- understand “human nature.” sitive fi nger tips are unique to us—in other apes they are narrow and hard and backed by very tough Human evolution and mirror neurons: nails—good for climbing and grabbing on surfaces Hands and tools but not for touch manipulation. Those fi nger pads revolutionized the hand by Many animals use and make tools including chim- giving the brain a vast range of complex and hierar- panzees and the New Caledonian crows. But no- chical motor goals linked to their touch awareness. thing compares to the abilities of our species— Here is where mirror neurons became important. from early infancy, we are described by child When you observe another person making delicate psychologists as “copying .” It is in part, fi nger movements, say when they tie a knot, you a result of our large brains being able to organize see their fi ngers moving sequentially in terms of the complex actions needed to fashion tools and their “touch space.” You see not so much fi nger then use them. Another factor is that hands are “de- movements as a sequence of fi nger goals. As a re- signed” to be dexterous. But I will argue a further sult, there is much more to motor mirror. Finger and factor was the prior existence of mirror neurons. thumb touch pads arose to make highly dexterous First, I will upon our hands—they differ fi nger actions, in particular, for manufacturing and from those of other apes but not in the way most using tools and artifacts. The usefulness of such people imagine (Napier, 1993). Other apes, like us skills, however, fi rst depended upon the ability to have an opposable thumb. And fi nger control of acquire them. When the organization of actions even monkeys can, like ours, be precise, for exam- are simple, an individual can learn them on their ple, when using their hands to feed delicately upon own, but with the complex ones needed to make seeds. Anatomically, slight variations in ligaments artifacts, an individual must pick them up—at least and muscles also exist. But the key difference is in part—from others. Thus, the brain’s ability to that humans do not use their arms and hands for get- imitate was critical in the evolution of fi nger pads ting about. Bipedality freed our upper bodies. The since without the ability to copy fi nger skills, there muscles, ligaments, joints and bones of our upper would be no advantage in them. Mirror neurons, of limbs as a result do not have to carry body weight course, played a key part in enabling such imitation when climbing or knuckle walking. That might and so the rise of our specialized fi ngers. seem a rather small point but the impact upon our arms and particularly our hands was enormous. It Vocalization enabled them to specialize without compromise in excellence in hand control. The fi ngers of chimpan- When we consider imitation, we think of hand mo- zees, for example are long and their thumbs short— vements or perhaps, the vocal copying of birds such adaptations which aid tree climbing and knuckle as parrots. We may be aware that we can imitate

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other individual’s speech but do not give it promi- 1998). Mirror neurons, in other words, in the past nence as a skill, nor as a key innovation in the ori- caused a mini natural selection upon speech sounds gin of language. That honor we give to syntax and with the criteria of survival being imitiability. semantics. But our abilities to mimic speech are remarkable and central to the existence of language Mirror neurons and our face (Skoyles, 1998). Other animals may communicate but humans are unique in doing so by means of a Mirroring is closely linked to sociability in vocabulary of many tens of thousands of words and certain animals, though not nonhuman primates names. The existence of vocabulary thus depends such as chimpanzees. Dolphins in particular show upon an ability to acquire all these thousands of spontaneous social imitation not only of each other pronunciations. Not just any means, but one that but even of humans. A human trainer making a head can do so in very young children in spite of the fact movement visible through a port hole in a tank to that their vocal organs have a different shape and a dolphin will see the dolphin trying to interact by size to adults and older children whose pronun- copying their movements—shaking their heads if ciations they copy. And, of course, such imitation the trainer shakes their own head (Delfour & Mar- must convert information contained in sound into ten, 2001). The sounds of dolphins also involve vocalizations. Thankfully, we are all rather good at much imitation. Recent research shows that dol- doing this, as can be seen when we shadow speech phins have as complex social lives as chimpanzees. containing unfamiliar words. After strokes, people Why then do dolphins but not chimpanzees use may lose their ability to initiate speech but can still mirroring in their sociability? The reason lies in what they hear other say. The size of a child’s the different opportunities for interaction offered vocabulary, as might be expected, depends upon by life in water compared to that on land. A chim- their earlier ability to repeat unfamiliar words. Part panzee can smell another, they can mutually groom, of the trick has been to make the sounds of speech and they live in a shared territory. Dolphins cannot those that are easiest to replicate. Though it tends do these things. Fortunately, life in water makes to get overlooked as an insignifi cant detail about imitation of movement and sound easy, which lets speech but its most elementary units, phones, are movement (together with sounds) take their place. scientifi cally characterized not in terms of audi- There is no problem of gravity. If a chimp copies tory sound but the manner and place in the vocal another’s movement its motor neurons must work track in which they are made. Indeed, one theory out the different effects of gravity upon its own and of hearing speech called—the “motor theory of the other individual’s movements. While this is speech perception”—argues that we hear words not impossible—we can do them all the time, they in terms of how they are articulated (Liberman & are a problem that dolphins in water can ignore (for Mattingly, 1985). the same reasons that astronauts to train for gravity- Here we can see a fundamental importance for free existence, do so in water tanks). mirror neurons—in fact two. First, vocabulary ba- Human evolution made mirroring much easier sed language got off the ground due to the ability for us than for a chimp. As noted, bipedality freed provided by mirror neurons to copy vocal articula- our hands to become highly dexterous because of tions. Second, such mirror neurons shaped the very imitation. And bipedality even itself aided mirro- vocalizations that make up speech. If you refl ect ring as it causes us to keep a constant posture— on it, learning vocabulary is a bottle neck upon the even when sitting we tend to keep our upper bodies development of speech. As such, it will powerfully in the vertical. Chimps, in contrast, live much of shape speech sounds by causing the preferential their lives in the horizontal plane as they climb and propagation of those sounds which are most easy knuckle walk. As a result, we present ourselves to copy. Sounds which are not so easy to imitate to each other in a much more constant position— will not be picked up by new speakers leaving only we rarely interact with people who are upside those speech sounds that are easy to copy (Skoyles, down. Moreover, because it is erect we are in the

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position which is most easy to see. That makes it primates, we are nearly entirely naked. See Skoyles easier to mirror each other. & Sagan, 2002.) But these merely aid mirroring—in contrast, There are other features linked to our visibility mirror neurons seem to have actively shaped our such as the reddening of our lips that make them faces. To appreciate this, look at your own face in a and their movements more easily seen, and that our mirror. Human faces—and your facial movements facial skin can blush. All together, this suggests that upon it—are unique among primates in having been our faces have been subject to a natural selection to selected to be easily seen. make them, and what happens on them, visible and First, alone amongst , the sclera of the distinct. Why? It is a story that, I suggest, involves human —the area surrounding our iris and pu- mirror neurons. pils—is exposed, wide and white. In other animals, Our faces are not only uniquely easy to see the surrounding area is either minimally exposed, or but also make movements that are worth looking dark to mask the visibility of the pupil. This makes at. One might invent a phrase and call our faces a sense: are easily spotted by predators and so “motor exposure board.” It is packed with mus- it advantages an animal to make them diffi cult to cles but it is the looseness of fl esh that makes their see. And for animals that are predators, they need movements so delicately and agilely expressive— to hide their eyes least their potential prey detect anatomically, we have much the same facial mus- them. But the human species has eyes that are visi- cles as chimpanzees (though our ones are more ble to onlookers—our sclera is exposed and white differentiated). Feel your face—what your fi ngers so that others can see it contrasted with our dark prod and massage is remarkably loose and soft— pupils. This does not advantage their function as there is nothing “leathery” about your face. This organs of sight but makes their movements highly subtle fl esh is exclusive to us. As a result we can noticeable (Kobayashi & Kohshima, 2001). much more agile use of our faces to make expres- A further difference is that compared with other sions. And not just the ones we see, but also micro apes, our faces are not framed by hair. Chimp fa- expressions that fl ash across it for a 15th of a second. ces are surrounded by fur—this makes them less If you look at real people talking at say a station easy to see. But human faces particularly those of or airport, you will see that people’s faces are in the young and women limit the presence of hair constant movement. except to the top of the head and above the eyes. But this is only the beginning of an explana- Having a “good head of hair” cuts the chance of tion—since why do we so persistently make these heat stroke that we risk when standing upright from agile facial movements when with others? The the overhead sun. Eye brows are also functional: obvious answer—and it is not entirely wrong—is they are in effect sweat bands that stop brow sweat that our faces enable us to communicate by making running down and stinging our eyes. (One needs facial gestures, the familiar expressions of smiles, here a brief distraction to mention that such swea- raised fearful eye brows, grimaces of disgust and ting and nakedness links to three unique features down turned sad mouths. There is a universal com- of our species. First, we can run energetically for munication system here—a smile says happiness many hours—most animals move fast only in brief whatever our language. But this expression of spurts. The reason for this is that we have a second emotion is only part of the story of our faces. For uniqueness: The adaptation to get rid of the heat a start, people are not that good at them as caused by the muscular exertion of constant ex- they confuse the expressions for fear and surprise, hausting activity by sweat evaporation. A runner, as well as the ones for anger and disgust. Further, for example, can during a marathon lose fi ve quarts chimps also use most of these expressions. In addi- of sweat. This in turn to a third uniqueness: tion to emotional expressions—which are easy to If we were covered with fur, that sweat could not study—we also engage when with others in what cool our bodies by evaporation—it would either might be called facial animation in activity that is drip off or form a sticky mess. Thus, unlike all other less easy to investigate. As noted, researchers that

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slow down videos of faces in communication fi nd cy since provides the cue for another related and that we make micro expressions that do not get linked expression. Mirror neurons responsible consciously noticed. But while they do not enter for expressions using the zygomaticus major and awareness, they are important as they let our faces corrugator supercilii get activated by the sight of say, “I heard you,” “it is now my turn,” “I am fo- facial expressions using them, and such activa- llowing what you say,” and “I am with you.” Our tion overfl ows to trigger the movements of these faces are not fl ashing out signs merely for “I am or other muscles. happy” or “I am sad”—they go far beyond this— Such mirroring, of course, helps smooth inter- they echo our social presence with each other. personal interaction, not only by making our faces William Condon of the University of Pittsburgh more communicative. We need to be able to pick up (1966) showed that people synchronize their voices information such as when people are losing interest with their body, arm and facial movements during in what we are saying, or seek a turn in the conver- conversation. He did this by looking at fi lm taken sation. But even this hardly begins to express the at 48 frames per second. As two people talked, he function of our faces which has to do with making was able to track a harmonious organization of and sharing social togetherness. Here we are dis- movements between their bodies and speech—“the cussing, not a skill but one of the things that is most body,” as he put it, “of the listener dances in rhythm intimate to us as real, living humans. Consider what with that of the speaker.” Thus, the animation of it would be like to have a face no one wants to inte- our hands and our motor exposure board—our ract with such as the “hideously” malformed one of faces—is a subtle mirror upon which we bounce off Joseph Carey Merrick, the “ man” (1862- expressions. The agility of the movement intercour- 1890). Facial deformity is a tragedy that really se can be a shock when we have nothing to do but should not rationally exist—after all, whatever the look at strangers in a public place. When engaged appearance of our faces it can still be functional in with others, the activity of faces does not register; allowing us to normally talk, breathe and eat, whi- but being outside a conversation we can see how le the movements of other parts of our bodies can subtly, agilely and exactly mouths contort, eyes take the place of turn taking in a conversation. They raise and head and hands jog about in rhythm with are in a way “redundant.” But if we imagine what it each other. People might feel they are only talking would be like being Joseph Merrick, we know that but they are also sharing social presence through they are critical to our existence—a display board an intricate facial and bodily tango. upon which we show and share our humanity. That Ulf Dimberg (1982) has researched how the is why the situation of Joseph Merrick touches us electromyclographic (EMG) responses of people’s so profoundly: he was human—but due to the gross face muscles such as the zygomaticus major and abnormality of his face, he was excluded, or nearly corrugator supercilii of observers react when they so, from sharing that humanity with others. Without see facial expressions made with these muscles. the efforts of Sir Frederick Treves, the actress Mrs. What Dimberg found is that we ever so slightly Kendall and other good hearted people, the human mirror in our own faces the expressions that we that was Joseph Merrick would have been a very see in others. Thus we are not only synchronizing isolated island at a freak show. The quotes around our movements, but also at the same time—at “hideous” above need to be there, he was not hi- least ever so slightly—mirroring them. People not deous—it is in us, not him that in which the horror only mimic the movements but mimicry strongly lies. Researchers that describe the function of our affects others. Tanya Chartrand (1999) has found faces as non-verbal communication therefore seem that people feel a strong rapport and personal liking to profoundly miss the point of having—or rather for an individual that copies their own movements. living as—a face. The facially deformed can make But more than copying is going on, as this hidden such communication or at least communicate their mirroring does not usually become the basis of equivalents. The tone of our voice, for example, an exact copy. What is reciprocated is contingen- can convey whether we are happy or not. What a

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person with a deformed face cannot do is the dance with each other as they engage in social commu- of interpersonal togetherness as few want to look nion. When we visit people in foreign places—we at a deformed face. feel a certain strangeness in their manners. People Our faces are therefore I suggest not so much interact with a different fl ow and rhythm to that communication devices but communion ones. with which we are familiar. There is nothing sur- The word “communion” comes from the Latin prising here since the fact that people have different communio which simply means “common.” Holy vocal accents is well recognized. People pick up the Communion in a service of common union—in- subtle ways of their social group in which we string dividuals which are separate are no longer so. together speech sounds. We do likewise in how we But the word can be used more widely: a dance articulate our faces and bodies when together. Or between two people can be cognitively—at least rather it is that our mirror neurons pick up these in motor terms—a communion. We do not com- subtle differences. municate anything by doing a waltz or rumba, we Mirror neurons thus tune us as belonging to use it to share a mutual social presence. What we do a particular group. Humans have a need for this is cease to be separate islands—for a moment the behavioral identifi cation of our home group since movements of two people interact and live as unlike other primates our sense of smell is much one. Behaviorally, two people organize themselves reduced (not least because standing upright our no- as if one body. Social communion not communica- se is in the wrong place). But that reduction could tion is the basis of our existence as social entities. only have happened because we could substitute a After all, little of what we say either by words behavioral alternative in its place. We, therefore, or nonverbal language concerns the pure transfer know a person belongs to our group not by how of information. Gossip, chit chat, the casual “how they smell but how they interact. We sniff, as it are you” patter of ordinary conversation may use were, the “accent” of their behavior, and sense a words that communicate information but what reassuring familiarity. But equally we can detect is being transacted is togetherness. We do not like a sense of strangeness. Mirror neurons, therefore, being alone. We seek relationships—we are an which have given us a powerful capacity to make immensely social —and our relationships social communion and so remove the boundaries need to be kept in repair. Our faces evolved as ex- which separate us as humans also as a result have a quisite display boards not to provide information powerful downside—in that they can also us to but to enable people to be with each other through experience other humans as lacking our humanity. social mirroring. Two computers, after all, might If people are of a different social group, we fail to communicate information between each other not sense what binds us together. Our feelings do not to transfer information but to check that they are resonant and as a result, it is easy to cease to care if still connected. we hurt them, or treat them in ways we would not We not only dance with each other nonverba- our own kin or kind. lly, but how we do so happens with a behavioral The role of mirror neurons in sociability makes accent or dialect. takes many forms but human experience very different to that of chim- one of them is how we bounce our expressions off panzees. Chimpanzees lack this ability to engage each other. The global variation in hand and facial with each other. They have little ability, for gestures is well known. To greet, Indians put their example, to share a mutual rhythm. In spite of the hands together on their chests in a praying position efforts of Sue Savage Rumbaugh to get Kanzi to while making a slight bow, Arabs sweep their right dance and bang away with her in tempo, he fi nds hand upward touching their hearts and foreheads, it hard to pace along with her. Mirror neurons by the Japanese bow, the Maoris of New Zealand rub synchronizing our interactions make us radically noses while Tibetan tribesmen stick their tongues different to chimps. Few children, after all, have out. Under this, as it were tip of an iceberg, there diffi culty in making a dance, beating a drum, or is a vast subtlety in how people nonverbally dance singing a song. To be human is to love to mirror

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what you do with what I do. This is not to say that dies—or at least our control of them—into those chimpanzees are not social and have as much need of others when viewing their situation and actions. as we do to be accepted. But that they do this instead Here neurons with which we organize behavior through olfaction and mutual grooming. Only hu- perceive what it would be to organize another’s mans create their sense of social existence through behavior given what they know and their goals. conversing or sharing music in the synchronized Interestingly, it is not a skill that all individuals activation of mirror neurons. possess. While those with Downs Syndrome have The mutual refl ecting of mirroring has the con- no problems with the Sally puppet task, those with sequence of forcing us to be equals. But this is not autism fi nd it hard. Or if they manage to answer always wanted, particularly if some individuals the task correctly, they do it oddly. Normally, we are more powerful and wanted to be treated wi- know spontaneously what Sally knows without th a high social status. Such individuals seek to any thought. But when those with autism manage stop the equality that comes with social mirroring. to answer correctly, they do so by working it out as That is not hard: if you can stop others seeing you, it were an intellectual problem. then you can prevent them striking up a relationship Controversy exists how far nonhuman primates with you as an equal. People can be stopped from, are able to read “minds.” Many of the cases which for example, in some it is an offense to we might feel show the evidence that chimps and look at royalty. And this can be achieved not only other animals can do this turn out to be explaina- by social taboos and rules about looking at each ble in terms of acquired associations. Even if they other. There are several reasons for the existence do, it seems they have such abilities only to a very of facial hair on mature men. For example, it marks limited extent compared to that of humans. This out dominant individuals in a group, like the lion’s is not to say other animals cannot empathize with main. But another a linked reason is that it makes suffering. Monkeys, for example, trained to pull a it harder for young men and women to mirror older cord for a food reward stop when they see that this men and so level their relationship with them. electrocutes a monkey in the next cage. But this does not originate in a theory of mind skill—very Mirror neurons and minds young infants also, for example, get upset with the suffering of others even though they are too young Mirror neurons underlie, it has been argued, our for this skill. It seems that mirror neurons while capacity to “put ourselves in other people’s shoes.” present in other primates fail to get used in cogni- Scientists call this “the theory of mind.” To illus- tion, while humans have exploited them to create trate what this involves, consider the following many diverse ways. Perhaps they had an even more test that uses a puppet story. First, the child sees profound effect upon us. a puppet called Sally who hides a marble in a and then goes away. While she is gone, they Beyond mirror neurons to human nature see another puppet enter and take the marble and put it into a covered box. The Sally puppet returns. You are reading this because you are interested in The child then is asked, “Where will Sally look for human nature. Every provides an answer her marble?” Answering this correctly requires an of some kind to this question. Why is this question ability to put ourselves in Sally’s position and see so important, however? I suggest it is more than what she might know. We have to put ourselves, as curiosity, and has to do with the central problem we say, in her shoes and so enter her inner world mirror neurons pose for our lives. If we create a and see what she might infer within. In a word, we sense of social togetherness through mirroring then need to mirror what is in her mind. it matters how similar we are—and with whom? This ability to put oneself in another’s shoes How easily will it be for me to mirror another? Is has been attributed to mirror neurons. After all, there some core nature in me and all other humans these enable us to put, as it were, our own bo- in which we can fi nd a common refl ection?

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During a talk upon whether animals suffer, a the question, How far are others like us? While we speaker switched in her slides without anyone no- may be physically separate, that due to mirror neu- ticing from asking whether animals had feelings to rons our minds are not. They provide a cognitive asking how they were like us. Questions about what communion, they prevent us experiencing indivi- is similar in our nature are not distant from those duals merely as objects but as having minds. about who has feelings. When we ask, say, whether There is another side to Seneca’s colamus hu- stones, snails, fi sh, cats, dogs, monkeys or apes manitatem, cherish humanity. Terence, an African have feelings—the question comes down to how slave that became one of Rome’s greatest drama- similar they are to us. But why should this be so? tists and poets once observed: homo sum: humani One answer is our mirror neurons. After all, if we nil a me alienum puto—I am a human being, so cannot mirror what is going on with another entity, nothing human is strange to me. We can now see we cannot attribute to it our own experiences such why. We care about each other not because we ra- as feelings. But what is similar? It does not have to tionally know that our bodies and experiences are be that of looks—we do not look like dogs—but we similar but because our awareness is built upon feel they have feelings. But we can empathize with the neurological equivalent of a mirror. Rationa- them since dogs mirror our social interactions with lity has nothing to do with it. Empathy is rooted them—it may be a tail wag rather than a smile— in the very process by which we form our sense of but the contingency to our own movements lets self. Part of our brains is, as it were, blind folded us “mirror.” Mirroring, similarity, feelings, and as to whether that pain is happening in our own our sense of the essence of ourselves—our human body or that of another. This gives us an automatic nature—are thus all intertwined. sense that another’s suffering is my business and unease—at least to prevent and heal. Mirror neu- Conclusions rons suggest we can never properly understand our nature in terms of being asocial individualists Natural selection created in us a brain that could or social egoists. Such limited social psychology care in a way which no other animal brain can. It did does not fi t in with the evolution of our brains this because it created a brain that mirrored other and so our minds. But mirror neurons offer us an individuals. At the most basic level this concerns opportunity to reappreciate such thinkers as John the animation which happens when we conver- Donne. Mirror neurons argue it is not merely theo- se. But from this foundation, it readily develops logy that “no man is an island, entire to itself,” or other cognitions built upon mirroring from which “Any man’s death diminishes me, because I am our humanity is built. It enables us to experien- involved in Mankind.” These are also truths of the ce others as having minds. It enables us to ask .

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Fecha de recepción: septiembre de 2007 Fecha de aceptación: marzo de 2008

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